Field of the Disclosure
This disclosure relates generally to the field of wafer processing equipment. More particularly, the present disclosure relates to a method and apparatus for controlling thermal emissivity of a heated stage and thereby controlling the temperature of wafers, such as semiconductor substrates.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Modern integrated circuits include semiconductor substrates or wafers. A wafer, also called a slice or substrate, is a thin slice of semiconductor material, such as a crystalline silicon, used in electronics for the fabrication of integrated circuits and in photovoltaics for conventional, wafer-based solar cells. The wafer serves as the substrate for microelectronic devices built in and over the wafer and undergoes many microfabrication process steps such as doping or ion implantation, etching, deposition of various materials, and photolithographic patterning. Finally the individual microcircuits are separated (dicing) and packaged.
Some high temperature processes require that the wafer be quickly cooled to room temperature to interrupt thermally induced chemical reactions on the wafer film. However, when the wafer is heated by a hot heated stage, the radiative coupling between the wafer and the heated stage couples the wafer cooling rate to that of the heated stage. This coupling may cause undesirable thermally induced chemical reactions on the wafer film.